“News that the agency admits it targeted American taxpayers based on politics is both astounding and appalling,” Camp said. The committee will “get to the bottom of this practice and ensure it never takes place again.”

The Oversight and Government Reform Committee, which has been busy investigating the attack in Benghazi, is also likely to hold hearings, sources said.

The committees are moving as quickly as possible to plan and schedule hearings, but witnesses need to be lined up.